US 5,187,475 A · Apparatus for determining the position of an object

Abstract

A position sensor is provided which incorporates the first and second magnetic members which are attached to an object whose position is to be determined. First and second magnetic sensors are disposed at positions in association with the two magnetic members. As the object moves along a predetermined path, the first and second magnetic members dispose a predetermined amount of magnetic material in the zones of the two sensors. By measuring the changing impedance of the winding of one of the sensors and comparing that value to the impedance of the winding of the other sensor, corrections can be made to determine the position of the object notwithstanding the fact that external effects may have changed the conditions under which the measurements are being taken. For example, gaps between the magnetic members and the sensors can possibly change from one time to another or the ambient temperature surrounding the sensors and the magnetic members could have changed. By comparing the values of the two sensor readings, these variabilities can be factored out of the determination and the accurate position of the object can be measured.

Claims20

Dependent claims

Apparatus for determining the position of an object, comprising:

a first sensor configured to provide a first signal responsive to the presence of a magnetic material proximate said first sensor;
a second sensor configured to provide a second signal responsive to the presence of a magnetic material proximate said second sensor;
a first magnetic member attached to said object, said first magnetic member having a first length defined along a first axis and a first cross sectional area, said first cross sectional area being generally perpendicular to said first axis;
and
a second magnetic member attached to said object, said second magnetic member having a second length defined along a second axis and a second cross sectional area, said second cross sectional area being generally perpendicular to said second axis, said first and second magnetic members being associated with said object to move along said first and second axes, respectively, in response to movement of said object, said first and second magnetic members being shaped to cause said first and second sensors to provide said first and second signals with relative magnitudes whose relationship is related to the position of said object.

2 more elements

An apparatus for determining the position of an object, comprising:

first means for sensing the presence of magnetic material in a first zone proximate said first sensing means, said first sensing means being responsive to the quantity of said magnetic material in said first zone;
second means for sensing the presence of magnetic material in a second zone proximate said second sensing means, said second sensing means being responsive to the quantity of said magnetic material in said second zone;
first means for moving a first quantity of said magnetic material into said first zone, said first moving means being attached to said object, said first quantity being independent from the position of said object;
second means for moving a second quantity of said magnetic material into said second zone, said second moving means being attached to said object, said second quantity being dependant on the position of said object;
first means for determining a first magnitude representative of said first quantity, said first determining means being connected in electrical communication with said first sensing means;
second means for determining a second magnitude representative of said second quantity, said second determining means being connected in electrical communication with said second sensing means;
and
means for comparing said first and second magnitudes to determine the position of said object.

5 more elements

Dependencies are inferred from the claim text.

Apparatus for determining the position of an object

Life of this patent

Apparatus for determining the position of an object

Life of this patent

Abstract

Claims20